<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>

	<body>
	</body>
	<script>
		off: function(types, selector, fn) {
			// ...

			if(selector === false || typeof selector === 'function') {
				// ( types [, fn] ) 的使用方式
				fn = selector
				selector = undefined
			}

			// ...
		}

		jQuery.fn.load = function(url, params, callback) {
			// ...

			if(isFunction(params)) {
				callback = params
				params = undefined
			}

			// ...
		}
	</script>

</html>